I bought my Kaisers through Gisele at Aid2Hearing. I wrote a little about the process here.
 
When I first twisted the K10s into my ears, plugged them into my iPhone and pressed play, the playlist I had ready sounded exactly as I had hoped - a bit dull and lifeless. In my experience the bigger the 'wow' at first listen, the more an earphone is likely to disappoint long term; initial 'thunderous' bass or 'twinkling' treble will often irritate my ears after a time. I have sensitive ears. After a pleasing enough listen with my iPhone, I tried several other players over the following months; you do not drop £1,400 on ear impressions and earphones to listen solely on an iPhone (no disclaimer needed here - I paid full whack for my K10s). 
 

 
The K10s are big. They stick out a little way from my ears, particularly at the top. This doesn’t bother me too much at home, but I tend to grab other IEMs for traveling - with the Kaisers I’m aware of these things sticking out of my ears when in public. They fit snugly, burrowing deep into my ear canals. Actually, they go deeper than any of my other earphones, giving the sensation of almost meeting in the middle or tickling my throat. It's an odd feeling, but one that passes after the initial insertion. 
 
The Kaiser 10s have an unusual configuration of their ten drivers: two low, two mid, two treble, two high treble and two ultra high treble. It’s something like that anyway, I can’t remember exactly; Noble removed the specs from their website a while ago. (Less information appears to be a trend at Noble. Their two-driver Savant, for example, was launched without the driver count being disclosed.)
 
The K10 sound is rich and weighty. If JH Audio’s JH13-Pro is a delicate Pinot Noir, Noble’s K10 is a full-bodied Cabernet Sauvignon. Bass and mid-range are at the fore, with treble slightly tucked behind. These monitors were created for listening pleasure rather than listening critically, though there is still plenty of detail.
 
Fed via my AK100 II’s optical output, I often set my Chord Hugo’s cross-feed to its lowest ‘on’ level and plug in my Noble K10s. I have to say this the best audio experience I have had thus far. Utterly immersive, realistic and three-dimensional. With orchestral music my mind paints a holographic picture of the orchestra. Violins over there. Trombones over there. Percussion back and right, solo clarinet centre-near. The timbre of each instrument is spot on. Really, spot on, without a hint of grating or harshness. Violins are scratchy yet still lush, trombones are raspy yet still musical. There is enough bite and edge in the sound to bring instruments to life, while retaining a smooth, open presentation. Just wonderful. Film scores are particularly engaging - I recommend those of John Barry or John Williams if you want to hear what I mean.
 
In the years (and money) I’ve spent on experimenting with setups I’ve gotten into the annoying and purposeless habit of listening for faults, rather than listening to music. In the Hugo/K10 combo I can honestly say that I cannot hear anything I dislike. Yes, the treble is a little distant but it sounds right. I don’t find myself yearning for a little more of this or that, or a bump in any frequency. I really get into the music once I have equipment I trust, and the K10s pass with full marks.
 
That the highs are a touch behind the mids and lows is remarkable when you consider that six of the ten drivers are allocated to the upper frequencies. I think the treble is done very well indeed. The bass is full and envelopes the whole sound wonderfully at times, though it is never too much. The mid range is stunning, but not in a obvious way. It’s just there, naturally. Think your Shure SE846 nails the mids? It does, but it comes well behind the K10 for pleasing, easy-listening realism.
 
With the K10, I found the AK120 II, iBasso DX90 and Oppo HA-2 a little too harsh (told you I have sensitive ears). I can’t describe why exactly. It’s almost as though too much electricity was rushing through my canals. On the other hand, the original AK120 and Chord Mojo* were unexciting, the sound being too thick and cluttered. Mojo sounds better than the AK120, though still a bit dark for my liking. I should add that the above sources are in comparison with my Hugo, and do not necessarily sound bad.
 
As far as lone DAPs go, the AK100 II hits the K10 sweet spot for me. I might be gushing about its sound had I not heard the Hugo.
 
I happily give five stars for the Kaiser 10. The combination with Hugo has given me an immense amount of pleasure over the past year or so. I like my K10s as much as I dislike the Wizard returns thread, which is a lot. My emotional buttons have been pressed more than a few times listening to my K10s, and that’s about the highest praise I can give.
 
 
*As a side note, I’ve spent a lot of time comparing Hugo with Mojo, reaching the conclusion that Mojo is Hugo minus its soul. Mojo is your mad aunt after she has undergone a course of electric shock treatment; ostensibly the same person but bereft of her vibrancy. This may not be the case with brighter earphones, but most of mine tend towards warm.

*I listened to the Westone 4Rs using iPhone 4S and the latest iPod Classic (6th Generation). The below sums up my listening experience from these sources only.*
 
The Westone 4Rs fit my ears better than any other earphones. With good tips, like Shure’s Grey Flex or ‘Olive’ tips, they feel snug without causing any discomfort. The nozzles on the 4R are shorter than that of Shure SE535 so the sound isolation isn’t quite as good, though they still do a reasonable job of blocking out external noise. As explained in the user manual, pulling your ears up and back helps to get a deeper fit when inserting.
 
The excellent cable is a sensible length (unlike the too-long Shure’s), tends not to tangle and has a short plastic ‘memory wire’, which keeps the Westones in place. The cable attaches to the earpiece with a two-pin connector, which is a less fiddly solution than the swivel connectors of Logitech’s UE 900 or Shure’s SE535.
 
The Westone 4Rs are warm tonally. I find their sound fairly balanced, with no frequency standing out above the others. The imaging is amazing too; there is a 3D quality that I’ve seldom heard from other earphones, though this only becomes apparent when the volume is quite loud.
 
I wanted to like these earphones, I really did. I ultimately sold them because they sound slightly veiled to me, as if the sound passes through a piece of material on its way from the drivers to my ears. I sensed a loss of sparkle and detail that I just couldn’t get past. I wouldn’t go as far as calling the sound muddy or cluttered, there just didn’t seem enough ‘air’ surrounding the music.

*I have listened to the Shure SE535 using iPhone 4S and the latest iPod Classic (6^th Generation). The below sums up my listening experience from these sources only.*
 
To my ears vocals sound better through the Shures than any other earphones I’ve heard. Voices are rich and clear. I often listen to audiobooks or Radio 4; just listening to people talking is a joy. However, I find the lower frequencies too thin. Bass is there, and is textured well enough to be able to distinguish between bass instruments, but it just doesn’t hit my ears with enough oomph to be pleasurable. I’m no ‘bass head’ but I do like to feel bass, not just hear it in the distance.
 
That the mid frequencies are louder that the bass or treble is one reason I sold my 535s. I noticed as time went by I wasn’t using them much; I was forcing myself to listen to them rather than being unable to take them out of my ears. I was listening to, rather than feeling and enjoying, music.
 
Physically, the Shure SE535s look good and appear to be well-made. Like Logitech’s newer UE 900, the earpiece has an unusual connection to the cable, which allows the earpiece to rotate when attached. I find that this, along with the long memory wire, is an unnecessary feature that makes them cumbersome to fit and insert. I much prefer the simple two pin plug of the Westone 4R. The cable itself is sturdy, but for me it is too thick and far too long. I like an earphone cable’s length to reach from trouser pocket to ear with a little slack. This one hangs down to my knees.
 
The nozzle you insert into your ear is quite long. With the right tips, this ensures good sound isolation. Many people like the foam “olive” tips. I do as well, but they can fit too tightly on the nozzle, making them difficult to remove. I snapped the nozzle off one earpiece when trying to twist a tip off.  [TIP: if the tip is stuck on the nozzle, put the earpiece in a bag in the freezer for a few hours. I’ve done this a few times and the tip comes off easily without damaging the earpiece.]
 
If you are looking for your first pair of ‘quality’ earphones, I recommend Logitech UE 900. I find that the Shure 535’s mid-range sound is wonderful and they block out more external noise, but the Logitech’s are a better overall package. Their sound is more balanced and they come with a very good accessories package.
 
If you already own the Shures and are looking for something a bit different, try Phonak’s Audeo PFE 232. The sound is like an inverted Shure SE535 sound signature, with excellent, strong bass and louder treble. I find their sound airy, fun and interesting, though they do not isolate sound well enough to be used in noisier environments.